Int 67 Fn 5DFF  U - Rm386 V6.00 - ???                                      [m]

   AX = 5DFFh
   ???

Return: ???

Note:  RM386 traps this function on the initial transition to protected
     mode caused by the INT instruction, which means it can not be
     overridden simply by hooking the interrupt

See Also: AX=5DFDh,AX=5DFEh